headfirst

1. Literally, with one's head at the forefront; leading with one's head. He tripped on a crack in the pavement and fell headfirst down a manhole. After debating it for several summers, Anna finally dove headfirst off the high dive at the community pool today. Would you please hold on to the railing? I don't want you to fall headfirst down those icy steps!

2. By extension, recklessly, brashly, or thoughtlessly. Before you go rushing headfirst into some half-baked business venture with these guys, take a minute and think about whether something like this could actually work. My brother was forever going headfirst into really serious relationships that would suddenly fizzle out a few months later. I don't question David's decision because he's not the type to rush headfirst into anything. I know he must have considered all of his options for a while.

ˌhead ˈfirst

1 moving forwards or downwards with your head in front of the rest of your body: He fell head first down the stairs.
2 without thinking carefully about something before acting: She got divorced and rushed head first into another marriage.